In recent years, with the maintenance expansion of network environments all over the world, Internet protocol (IP) telephony has been spread using an Internet line in addition to a telephone line of a related art. In the IP telephony, users have a conversation with each other by communicating an audio or image signal according to the Internet protocol using a personal computer (PC) connected to the Internet line, a mobile phone with a local area network (LAN) function, or the like.
Among the IP telephony, particularly, a service called a Skype is widely spread across the world, and there are hundreds of millions of registered users. In the beginning, the IP telephony using the Skype supported only a voice call, but as the speed of the network is increased, and terminal devices become high functionality, the IP telephony using the Skype is currently able to perform a video call supporting a high-definition video and thus being used by many people.
In such a video call, since an image imaged by a camera is transmitted to a call counterpart without change, there may be a problem in terms of the user's privacy. For this reason, a technique of extracting a contour of the user from an acquired image and synthesizing a clipped image of the user with a background image was proposed in Patent Document 1. A method of automatically selecting a background image according to an incoming call telephone number was proposed in Patent Document 2.